CI: Pin base image to Fedora 34 for now
CI: Pin base image to Fedora 34 for now

The current image based on Fedora 35 gives timeout in tests using
D-Bus.  Until we figure out the cause, let's stick with Fedora 34.

GNOME/libsecret,GNOME/libsecret,GNOME/libsecret,GNOME/libsecret